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This code repository contains the U.S. Reference Software Implementation of Recommendation ITU-R P.528. This Recommendation contains a method for predicting basic transmission loss in the frequency range 100-30 000 MHz for aeronautical services. The software implements Annex 2 of Rec P.528, the Step-by-Step method to computing propagation loss for air-to-ground paths.
Companion software (p528-gui) provides a Graphical User Interface (GUI) that can be used with this software implementation.
| Variable | Type | Units | Limits | Description |
|---|---|---|---|---|
d__km | double | km | 0 <= d__km | Great circle path distance between terminals |
h_1__meter | double | meter | 1.5 <= h_1__meter <= 20 000 | Height of the low terminal |
h_2__meter | double | meter | 1.5 <= h_2__meter <= 20 000 | Height of the high terminal |
f__mhz | double | MHz | 100 <= f__mhz <= 30 000 | Frequency |
T_pol | int | Polarization
| ||
time | double | 1 <= time <= 99 | Time percentage |
Outputs to P.528 are contained within a defined Results structure.
| Variable | Type | Units | Description |
|---|---|---|---|
d__km | double | km | Great circle path distance. Could be slightly different than specified in input variable if within LOS region |
A__db | double | dB | Basic transmission loss |
A_fs__db | double | dB | Free space basic transmission loss |
A_a__db | double | dB | Median atmospheric absorption loss |
theta_h1__rad | double | rad | Elevation angle of the ray at the low terminal |
propagation_mode | int | Mode of propagation
| |
warnings | int | Warning flags |
P.528 supports a defined list of error codes and warning flags. A complete list can be found here.
The below table includes a select set of example inputs and outputs for testing purposes. The P.528 CSV data files contain an extensive set of validation example values.
d__km | h_1__meter | h_2__meter | f__mhz | T_pol | time | A__db |
|---|---|---|---|---|---|---|
| 15 | 10 | 1 000 | 500 | 0 | 50 | 110.0 |
| 100 | 100 | 15 000 | 3 600 | 0 | 90 | 151.6 |
| 1 500 | 15 | 10 000 | 5 700 | 0 | 10 | 293.4 |
| 30 | 8 | 20 000 | 22 000 | 1 | 50 | 151.1 |
- In general, variables follow the naming convention in which a single underscore denotes a subscript (pseudo-LaTeX format), where a double underscore is followed by the units, i.e. h_1__meter.
- Variables are named to match their corresponding mathematical variables in the underlying Recommendation text.
- Wherever possible, equation numbers are provided. It is assumed that a user reviewing this source code would have a copy of the Recommendation's text available as a primary reference.
The software is designed to be built into a DLL (or corresponding library for non-Windows systems). The source code can be built for any OS that supports the standard C++ libraries. A Visual Studio 2019 project file is provided for Windows users to support the build process and configuration.
The .NET support of P.528 consists of a simple pass-through wrapper around the native DLL. It is compiled to target .NET Framework 4.8. Distribution and updates are provided through the published NuGet package.
For questions, contact Billy Kozma, wkozma@ntia.gov